The earliest mention of Kashgar occurs when a Chinese Han Dynasty (206 BCE  220 CE) envoy traveled the Northern Silk Road to explore lands to the west. Another early mention of Kashgar is during the Former Han (also known as the Western Han Dynasty), when in 76 BCE the Chinese conquered the Xiongnu, Yutian (Khotan), Sulei (Kashgar), and a group of states in the Tarim basin almost up to the foot of the Tian Shan mountains. Ptolemy spoke of Scythia beyond the Imaus, which is in a 'Kasia Regio', probably exhibiting the name from which Kashgar is formed. The countryˇs people practised Zoroastrianism and Buddhism before the coming of Islam. The celebrated Old Uighur prince Sultan Satuq Bughra Khan converted to Islam late in the 10th century and his Uighur kingdom lasted until 1120 but was distracted by complicated dynastic struggles. The Uighurs employed an alphabet based upon the Syriac and borrowed from the Nestorian, but after converting to Islam widely used also an Arabic script. They spoke a dialect of Turkic preserved in the Kudatku Bilik, a moral treatise composed in 1065.